With recent trends toward more environmental regulations and energy consciousness on the part of end users, vehicular rotating electric machines are being required to offer high output and high efficiency and improvements are proposed on stators that produce a particularly great effect.
In general, a stator used in a rotating electric machine includes a stator core and a stator winding. The stator core has a plurality of slots arrayed circumferentially and opening in an inner peripheral surface. The stator winding is formed of a continuous wire into a wave. A winding pitch of an annular coil used for the stator winding is a full-pitch winding and the stator winding is inserted in each slot across a plurality of teeth. A rotor includes a pair of rotor cores having claw-shaped magnetic poles that are disposed such that claw portions face each other and one claw-shaped magnetic pole engages with another.
A known technique incorporates a fractional-pitch winding for the winding pitch of the annular coil used for the stator winding, thereby adopting a winding style of an array of a plurality of annular coils, instead of the conventional wave winding. The technique thereby provides a low-cost, high output, and high efficiency rotating electric machine with reduced resistance achieved by a shorter coil length (see Patent Document 1).